Operation detecting apparatus for vehicle

ABSTRACT

An operation detecting apparatus for a vehicle includes: a detecting unit including a first electrode and a second electrode for detecting variations in capacitance value; a capacitance measuring unit configured to measure a first capacitance value detected by the first electrode and a second capacitance value detected by the second electrode; a determining unit configured to compare a value on the basis of an amount of variations in the first capacitance value with a value on the basis of an amount of variations in the second capacitance value and determine presence or absence of operation from a user on the basis of the result of comparison; and an output unit configured to output a control signal on the basis of a result of determination of the determining unit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 U.S.C. §119 toJapanese Patent Application 2014-234149, filed on Nov. 19, 2014, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an operation detecting apparatus for avehicle in which a capacitance sensor is used.

BACKGROUND DISCUSSION

A capacitance sensor configured to detect positions or actions ofdetected objects by a change in capacitance is known. The capacitancesensor includes one or more electrodes for detection. When the detectedobject approaches the electrode for detection, a capacitance valuegenerated between an electrode and an electrode, or between an electrodeand the ground varies. The capacitance sensor is an apparatus configuredto detect actions of the detected objects by measuring the change incapacitance value as an electric signal.

JP 2006-213206 A discloses a vehicle window sensor configured to detectvariations in capacitance between two electrodes including a sensorelectrode installed on a window glass of a vehicle as one electrode, anda vehicle body as the other electrode.

The vehicle window sensor disclosed in JP 2006-213206 A is configured todetect the capacitance between the electrode on the window glass and thevehicle body and thus has a wide detecting area. In the case where thevehicle window sensor is used as an operation detecting unit, thevehicle window sensor has a potential to detect operation erroneouslyeven though a user does not perform operation such as the case where aperson passes near by the vehicle at the time of parking.

SUMMARY

Thus, a need exists for an operation detecting apparatus for a vehiclewhich is not suspectable to the drawback mentioned above.

An aspect of this disclosure provides an operation detecting apparatusfor a vehicle including a detecting unit having a first electrode and asecond electrode configured to detect variations in a capacitance value;a capacitance measuring unit configured to measure a first capacitancevalue detected by the first electrode and a second capacitance valuedetected by the second electrode; a determining unit configured tocompare a value on the basis of the amount of variations in the firstcapacitance value with a value on the basis of an amount of variationsin the second capacitance value and determine presence or absence ofoperation from a user on the basis of the result of comparison; and anoutput unit configured to output a control signal on the basis of aresult of determination of the determining unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of thisdisclosure will become more apparent from the following detaileddescription considered with the reference to the accompanying drawings,wherein:

FIG. 1A is a block diagram illustrating a configuration of a capacitancesensor of an opening and closing member for a vehicle according to afirst embodiment;

FIG. 1B is a block diagram illustrating a configuration of a capacitancemeasuring unit of the opening and closing member for a vehicle accordingto the first embodiment;

FIG. 2A is a drawing illustrating a configuration of a capacitancesensor electrode according to the first embodiment;

FIG. 2B is a cross-sectional view of the capacitance sensor electrodeaccording to the first embodiment taken along a line IIB-IIB′;

FIG. 2C is a drawing illustrating detection of capacitance variations inthe capacitance sensor electrode according to the first embodiment;

FIG. 3 is a drawing illustrating a condition in which a person standsnear by the capacitance sensor electrode;

FIG. 4A is a drawing illustrating a condition in which a user operatesthe capacitance sensor electrode by hand;

FIG. 4B is a drawing illustrating a condition in which the user operatesthe capacitance sensor electrode by hand;

FIGS. 5A and 5B are graphs illustrating amount of variations incapacitance value when a detected object is brought closer and then awayfrom the capacitance sensor electrode;

FIG. 6 is a flow chart illustrating a method of controlling thecapacitance sensor according to the first embodiment;

FIG. 7A is a drawing illustrating a configuration of a capacitancesensor electrode according to a second embodiment;

FIG. 7B is a cross-sectional view of the capacitance sensor electrodetaken along a line VIIB-VIIB′ in the second embodiment;

FIG. 7C is a drawing illustrating detection of the capacitancevariations in the capacitance sensor electrode according to the secondembodiment;

FIG. 8 is a drawing illustrating a mounting position of the capacitancesensor electrode on a vehicle according to the second embodiment;

FIG. 9A is a drawing illustrating a condition in which a person standsnear by the capacitance sensor electrode;

FIG. 9B is a drawing illustrating a condition in which a user operatesthe capacitance sensor electrode by foot;

FIGS. 10A and 10B are drawings illustrating a modification of amutual-capacitance type capacitance sensor electrode; and

FIGS. 11A to 11E are drawings illustrating a modification of aself-capacitance type capacitance sensor electrode.

DETAILED DESCRIPTION

Exemplary embodiments for implementing this disclosure will be describedwith reference to the drawings. However, unless otherwise specificallynoted, the scope of this disclosure is not limited to modes described indetail in the embodiments set forth below. In the drawings which will bedescribed below, the same components having the same functions aredenoted by the same reference numerals, and repeated descriptions may beomitted.

First Embodiment

FIG. 1A is a block diagram illustrating a configuration of an operationdetecting unit used for an opening and closing member for a vehicle(slide door, rear door, and the like) according to a first embodimentdisclosed here. A capacitance sensor 100, which corresponds to theoperation detecting unit used for the opening and closing member for avehicle includes a capacitance sensor electrode 110 and a capacitancesensor control unit 120. The capacitance sensor electrode 110 is adetecting unit of the capacitance sensor 100 configured to detectoperation of the opening and closing member for a vehicle by a user. Thecapacitance sensor control unit 120 is a portion configured to controloperation of the capacitance sensor electrode 110 and output the resultof detection obtained by the capacitance sensor electrode 110 to anopening and closing member control device 140.

The capacitance sensor 100 of the embodiment is of a mutual-capacitancetype. The capacitance sensor electrode 110 includes a transmittingelectrode 111, a first receiving electrode 112, and a second receivingelectrode 113. The transmitting electrode 111 is an electrode configuredto generate lines of electric force by applying voltage, and the firstreceiving electrode 112 and the second receiving electrode 113 areelectrodes that receive the lines of electric force. Accordingly,capacitance is generated between the transmitting electrode 111 and thefirst receiving electrode 112 and between the transmitting electrode 111and the second receiving electrode 113. The capacitance sensor 100 ofthe embodiment is configured to detect approach and separation of adetected object such as a hand of the user by measuring variations incapacitance.

The capacitance sensor electrode 110 may be installed at any position ofthe vehicle as long as the user can operate and the lines of electricforce are not interrupted by the conductive member. For example, thecapacitance sensor electrode 110 may be installed on a door handle, acenter pillar (a column on the side surface of the vehicle and providedat a position between a front seat and a rear seat), a center pillargarnish, a belt molding, a rear side of an emblem, a rear door garnish,and a bumper. The capacitance sensor electrode 110 may be installed on amovable member of an opening and closing member 150 for the vehicle ormay be installed in other portions. Furthermore, in a case where aportion of the member which constitutes the opening and closing memberis not formed of a metal, the capacitance sensor electrode 110 may beinstalled on an inner side of a portion which is not formed of themetal.

The capacitance sensor control unit 120 includes a bus 121, ameasurement control unit 122, a determining unit 123, an operating unit124, a memory 125, a timer 126, a control signal I/O unit 127, and acapacitance measuring unit 130. The bus 121 is wiring configured toconnect respective portions of the capacitance sensor control unit 120.The capacitance measuring unit 130 is a portion that measures acapacitance between the respective electrodes of the capacitance sensorelectrode 110.

The control signal I/O unit 127 is a portion corresponding to aninterface that sends and receives a signal between the capacitancesensor measuring unit 120 and the opening and closing member controldevice 140. The control signal I/O unit 127 functions as an output unitconfigured to output a signal relating to a user operation such aspresence or absence of the operation by the user by using thecapacitance sensor electrode 110 to the opening and closing membercontrol device 140. The control signal I/O unit 127 functions also as aninput unit configured to receive signals which indicate the state of theopening and closing member 150 (opened state and closed state) from theopening and closing member control device 140.

The opening and closing member control device 140 is, for example, anECU (Electronic Control Unit) mounted on a vehicle, and controls anopening and closing operation of the opening and closing member 150 onthe basis of the signal indicating the operation by the user input fromthe control signal I/O unit 127 of the capacitance sensor control unit120. The opening and closing member 150 is an opening and closing memberfor a vehicle configured to perform an opening and closing operationautomatically by a drive source such as a motor. More specifically, theopening and closing member 150 may include a slide door, a sun roof, arear door, a power window, a swing door and the like. The opening andclosing member 150 is provided with a sensor configured to detect astate of operation of the drive source. For example, the opening andclosing member 150 may be provided with a pulse sensor using a Hallelement as a sensor configured to detect a rotation of the motor. Anoutput from the sensor is output from the opening and closing member 150to the opening and closing member control device 140, and is input intothe determining unit 123 via the control signal I/O unit 127 of thecapacitance sensor control unit 120. The output of the sensor may beheld once in the memory 125 without being directly input into thedetermining unit 123, and then read out by the determining unit 123.

The measurement control unit 122 is a portion configured to control astate of measurement of the capacitance measuring unit 130. For example,the state of connection of the switch 131 is switched by the outputsignal from the measurement control unit 122. Accordingly, either one ofmeasurement by the first receiving electrode 112 and measurement by thesecond receiving electrode 113 may be selected.

The memory 125 includes a ROM and a RAM, and is a memory mediumconfigured to temporarily or permanently memorise data such as an outputvalue from the capacitance measuring unit 130, time or duration ofoutput from the timer 126, or the state of the opening and closingmember 150 output from the opening and closing member control device140. The memory 125 supplies data memorised in accordance withinstruction from the determining unit 123 and the operating unit 124.The timer 126 is a portion configured to provide time information to therespective members.

The determining unit 123 is a portion configured to determine whether ornot normal operation is performed by the user on the basis of the outputvalue from the capacitance measuring unit 130 memorised in the memory125. The normal operation is a specific operating procedure which isperformed when the user indicates a wish to open or close the openingand closing member 150.

The operating unit 124 is a portion configured to perform reduction ofnoise, offset elimination, and various computations for data processingsuch as multiplication of coefficient on an output signal indicating thecapacitance value output from the capacitance measuring unit 130.

FIG. 1B is a block diagram illustrating a configuration of a capacitancemeasuring unit of an opening and closing member for a vehicle accordingto the first embodiment. The capacitance measuring unit 130 includes aswitch 131, a voltage supply portion 132, a CV (Capacitance-to-Voltage)converting unit 133, and an AD (Analogue-to-Digital) converting unit134.

The voltage supply portion 132 is a portion configured to supply avoltage for outputting the lines of electric force to the transmittingelectrode 111 in accordance with the control signal from the measurementcontrol unit 122 input via the bus 121. The voltage supply portion 132may include a voltage conversion circuit, an amplifier circuit, and thelike for adjusting the voltage to be supplied to the transmittingelectrode 111.

The switch 131 is a portion configured to change over connections of theelectrodes, for example, for selecting an electrode that measures thecapacitance. The switch 131 includes a portion that switches ON and OFFbetween the transmitting electrode 111 and the voltage supply portion132. The switch 131 further includes a portion that switches theconnection of the CV converting unit 133 either to the first receivingelectrode 112 or to the second receiving electrode 113.

The CV converting unit 133 is a CV conversion circuit configured toconvert the capacitance between the transmitting electrode 111 and thefirst receiving electrode 112 or the capacitance between thetransmitting electrode 111 and the second receiving electrode 113 into avoltage value and output the voltage value. The CV converting unit 133may include an amplifier configured to vary an output voltage at thetime of CV conversion.

The AD converting unit 134 is an AD conversion circuit configured toconvert the voltage value output from the CV converting unit 133 to adigital signal and output the digital signal. The digital signalindicating a capacitance value output from the AD converting unit 134 isheld in the memory 125 via the bus 121.

In the first embodiment, the capacitance measuring unit 130 includes acircuit configured to perform measurement of the capacitance by the CVconversion circuit. However, measurement of the capacitance may beperformed by other methods. For example, a capacitance measuring methodwith various circuits such as a circuit configured to repeatedlytransfer an electric charge to a reference capacitative element andcount the number of times of transfer, or a CR resonance circuit.

One of more functional portions disclosed here and illustrated in FIG.1A and FIG. 1B may be provided by hardware, or may be provided byprograms which are operated on hardware of a computer including a CPU(Central Processing Unit). These programs may be stored in the memory125.

FIG. 2A is a drawing illustrating a configuration of the capacitancesensor electrode 110 according to the first embodiment. FIG. 2B is across-sectional view of the capacitance sensor electrode according tothe first embodiment taken along a line IIB-IIB′. The transmittingelectrode 111, the first receiving electrode 112, and the secondreceiving electrode 113 of the capacitance sensor electrode 110 areformed on a main surface of a thin-plate-shaped base member 211. Thebase member 211 is formed of a high-resistance material or an insulativematerial such as resin, glass, and ceramics. The base member 211 has anelliptical shape. The transmitting electrode 111 is arranged in thevicinity of a long axis of the base member 211. The first receivingelectrode 112 and the second receiving electrode 113 are arranged onboth sides of the transmitting electrode 111. A gap 212 is formedbetween the first receiving electrode 112 and the transmitting electrode111. A gap 213 is formed between the second receiving electrode 113 andthe transmitting electrode 111. The length in a long side direction ofthe first receiving electrode 112 is smaller than that of the secondreceiving electrode 113. In other words, a surface area of the firstreceiving electrode 112 is smaller than a surface area of the secondreceiving electrode 113. Arrangement and shapes of the base member 211,the transmitting electrode 111, the first receiving electrode 112, thesecond receiving electrode 113, and the gaps 212 and 213 as illustratedin FIG. 2A are not essential and may be modified as needed.

FIG. 2C is a drawing illustrating detection of the capacitancevariations in the capacitance sensor electrode 110 according to thefirst embodiment. When a voltage is applied to the transmittingelectrode 111, lines of electric force are transmitted from thetransmitting electrode 111. Some of the lines of electric forcetransmitted from the transmitting electrode 111 are received by thefirst receiving electrode 112. Accordingly, capacitance is generatedbetween the transmitting electrode 111 and the first receiving electrode112. In the same manner, the capacitance is also generated between thetransmitting electrode 111 and the second receiving electrode 113.

FIG. 2C illustrates a distribution of the lines of electric force in thecase where a detected object 214 having conductivity such as a humanhand approaches the gap 212 between the transmitting electrode 111 andthe first receiving electrode 112. The detected object 214 equivalentlyfunctions as the ground, and thus the lines of electric forcetransmitted from the transmitting electrode 111 are interrupted by thedetected object 214. Accordingly, the capacitance between thetransmitting electrode 111 and the first receiving electrode 112 isreduced. The reduction of the capacitance is measured via the firstreceiving electrode 112, so that approach and separation of the detectedobject 214 are detected. The same applies to the case where the detectedobject 214 approaches the second receiving electrode 113. In otherwords, the capacitance sensor electrode 110 of the first embodiment hastwo detecting areas, and thus is applicable to measurement in twochannels. In this specification, the detecting area indicates a spatialrange in which variations in capacitance can be detected when thedetected object 214 enters.

In this manner, the capacitance sensor electrode 110 of the firstembodiment includes two detecting areas on the basis of a capacitancevalue (first capacitance value) between the transmitting electrode 111and the first receiving electrode 112 and a capacitance value (secondcapacitance value) between the transmitting electrode 111 and the secondreceiving electrode 113. On the basis of the control from themeasurement control unit 122, the capacitance measuring unit 130measures these capacitance values repeatedly and continuously orintermittently to cause the memory 125 to hold data indicating the firstcapacitance value and data indicating the second capacitance valuerepeatedly.

The determining unit 123 of the capacitance sensor 100 according to thefirst embodiment determines whether or not the detected object hasapproached on the basis of an amount of variations ΔC1 of the firstcapacitance value, and determines whether or not the amount ofvariations ΔC1 of the first capacitance value is a variation caused bythe user operation on the basis of an amount of variations ΔC2 of thesecond capacitance value. In other words, the first receiving electrode112 functions as a detecting electrode for the user operation, and thesecond receiving electrode 113 functions as the electrode for detectingerroneous detection. Accordingly, the erroneous detection caused by thevariations in capacitance not on the basis of the user intention. Thedetermination of the user operation will be described.

Hereinafter, ΔC1 and ΔC2, which are “amount of variations in capacitancevalue” are each defined to mean an absolute value of a differencebetween a measured value of the capacitance at a certain point of timeand a reference capacitance value when the detected object does notapproach. In the first embodiment, since the capacitance sensor 100 isof the mutual-capacitance type, if the detected object approaches thecapacitance sensor electrode 110, the capacitance value decreases.However, since the “amount of variations in capacitance value” isabsolute values, the capacitance value is a positive value.

In the case where the first capacitance value or the second capacitancevalue varies, the determining unit 123 determines absence or presence ofthe user operation in accordance with a table given below in the casewhere the first capacitance value or the second capacitance valuevaries.

TABLE 1 Condition A Condition B Condition C ΔC1 ΔC1 < threshold ΔC1 ≧threshold ΔC1 ≧ threshold value value value ΔC2 any value ΔC1 < ΔC2 ΔC1≧ ΔC2 Determination No user operation No user operation User operationis of User performed Operation State of Sensor No detected Detectedobject is User is operating object present but not user operation

Condition A is a condition in which the detected object 214 such as aperson or the like is not in proximity to the capacitance sensorelectrode 110. In this condition, the amount of variations ΔC1 of thefirst capacitance value indicates zero or a sufficiently small value.When a predetermined threshold set in view of noise or the like has arelationship ΔC1<threshold value, the determining unit 123 determinesthat the condition falls under Condition A and thus the user operationis not performed. In this case, the amount of variations ΔC2 of thesecond capacitance value is not used for determination.

Condition B is a condition in which the detected object 214 such as aperson or the like is in proximity to the capacitance sensor electrode110 but no user operation is performed. As a specific example, a casewhere the person is standing near the capacitance sensor electrode 110but that person has no intention to open or close the opening andclosing member 150 is exemplified.

FIG. 3 is a drawing illustrating a condition in which a person isstanding near by the capacitance sensor electrode 110, which correspondsto Condition B. The capacitance sensor electrode 110 illustrated in FIG.2A to FIG. 2C is installed vertically, and the person stands nearby withhis or her back facing thereto. At this time, a first detecting area 301is formed by the lines of electric force between the transmittingelectrode 111 and the first receiving electrode 112 in the vicinity ofthe capacitance sensor electrode 110. In the same manner, a seconddetecting area 302 is formed by the lines of electric force between thetransmitting electrode 111 and the second receiving electrode 113. Asdescribed above, the surface area of the first receiving electrode 112is smaller than the surface area of the second receiving electrode 113,and thus the first detecting area 301 is smaller than the seconddetecting area 302. In other words, in Condition B, the amount ofvariations ΔC1 of the first capacitance value caused by the back of theperson as the detected object 214 is smaller than the amount ofvariations ΔC2 of the second capacitance value. Therefore, whenrelationships ΔC1≧threshold value and ΔC1<ΔC2 are satisfied, thedetermining unit 123 determines that the condition falls under ConditionB, and the user operation is not performed.

Condition C is a condition in which the user operates the capacitancesensor electrode 110 with an intention to open and close the opening andclosing member 150. FIG. 4A and FIG. 4B are drawings illustrating astate in which the user operates the capacitance sensor electrode 110with his or her hand. FIG. 4A is a drawing of the capacitance sensorelectrode 110 viewing from the front, and FIG. 4B is a drawing of thecapacitance sensor electrode 110 viewing from the side.

As illustrated in FIG. 4A and FIG. 4B, normal operation of thecapacitance sensor 100 of the first embodiment is an action of the userapproaching fingertips to the position near by the first receivingelectrode 112 (holding operation). In this case, as illustrated in FIG.4B, fingers are in the proximity to the first detecting area 301, butthe fingers or the palm does not approach the position near by thesecond detecting area 302. In other words, in Condition C, the amount ofvariations ΔC1 of the first capacitance value caused by the hand of theperson as the detected object 214 is not smaller than the amount ofvariations ΔC2 of the second capacitance value. Therefore, whenrelationships ΔC1≧threshold value and ΔC1≧ΔC2 are satisfied, thedetermining unit 123 determines that the condition falls under ConditionC, and the user operation is performed.

FIGS. 5A and 5B are graphs illustrating relationships between the amountof variations ΔC1 of the first capacitance value and the amount ofvariations ΔC2 of the second capacitance value with time when thedetected object is approached and then separated. In the respectivegraphs, solid lines indicate the amount of variations ΔC1 of the firstcapacitance value, and broken lines indicate the amount of variationsΔC2 of the second capacitance value. At clock times T1 and T3, thedetected object starts to approach the detecting area of the capacitancesensor electrode 110, and at clock times T2 and T4, the detected objectleaves the detecting area of the capacitance sensor electrode 110.

FIG. 5A illustrates variations in capacitance value when the useroperation is performed. From the drawing, the amount of variations ΔC1of the first capacitance value is larger than the threshold value whenthe detected object approaches, and is larger than the amount ofvariations ΔC2 of the second capacitance value. In other words,relationships ΔC1≧threshold value and ΔC1≧ΔC2 are satisfied, and thedetermining unit 123 determines that the condition falls under ConditionC and the user operation is performed.

FIG. 5B illustrates variations in capacitance value when the substancehaving a large surface area which corresponds to the back of a personapproaches the capacitance sensor electrode 110. From the drawing, whenthe detected object approaches, the amount of variations ΔC1 of thefirst capacitance value is larger than the threshold value, and issmaller than the amount of variations ΔC2 of the second capacitancevalue. In other words, relationships ΔC1≧threshold value and ΔC1<ΔC2 aresatisfied, and the determining unit 123 determines that the conditionfalls under Condition B and the user operation is not performed.

In this manner, by the determination on the basis of a plurality of theamounts of variations in capacitance value, the determining unit 123 iscapable of determining the presence or absence of the user operationcorrectly, and the erroneous operation caused by the capacitancevariations which are not generated by the normal operation is prevented.

FIG. 6 is a flowchart illustrating a method of controlling thecapacitance sensor 100 according to the first embodiment. The flowchartof FIG. 6 describes a control flow when the user performs the openingand closing operation with respect to the capacitance sensor electrode110 when the opening and closing member 150 is stopped or is operated.This flowchart is illustrated so as to start from START and end at END.However, since the timing when the user performs the operation isirregular, the control flow is preferably performed continuously orintermittently in a repeated manner. However, under the condition inwhich the opening and closing operation of the opening and closingmember 150 does not seem to be performed, such as during travel, thiscontrol flow may be stopped.

In Step S601, the capacitance sensor 100 measures the capacitance valuefor detecting the holding operation by the user. Specifically, thecapacitance measuring unit 130 performs measurement of the capacitancevalue between the transmitting electrode 111 and the first receivingelectrode 112 (first capacitance value) and measurement of thecapacitance value between the transmitting electrode 111 and the secondreceiving electrode 113 (second capacitance value) alternately in arepeated manner, and causes the memory 125 to hold a result ofmeasurement.

In Step S602, the determining unit 123 determines whether or not theamount of variations ΔC1 of the first capacitance value is larger thanthe predetermined threshold value. In the case where the relationshipΔC1<threshold value is satisfied, the determining unit 123 determinesthat the condition falls under Condition A, and the user operation isnot performed (NO in step S602). The flow is then terminated. In thecase where the relationship ΔC1≧threshold value is satisfied, the flowproceeds to Step S603 (YES in Step S602).

In Step S603, the determining unit 123 determines whether or not theamount of variations ΔC1 of the first capacitance value is larger thanthe amount of variations ΔC2 of the second capacitance value. If therelationship ΔC1<ΔC2 is satisfied, the determining unit 123 determinesthat the condition falls under Condition B, the user operation is notperformed (NO in Step S603). The flow is then terminated. If therelationship ΔC1≧ΔC2 is satisfied, the determining unit 123 determinesthat the condition falls under Condition C, and the user operation isperformed (YES in Step S603). In this case, the flow proceeds to StepS604.

In Step S604, the determining unit 123 outputs a signal indicating thatthe user has performed operation for stopping the action of the openingand closing member 150 to the opening and closing member control device140. Accordingly, the opening and closing member control device 140controls the opening and closing member 150 to stop. When the stopcontrol is performed, the flow is terminated.

The order of Step S602 and Step S603 may be vise versa or may besimultaneous. The flow may be modified so as to determine that the userhas performed operation in the case where both of conditions determinedin Step S602 and Step S603 are continued for a predetermined period.

In the first embodiment, the first receiving electrode 112 functions asa detecting electrode for the user operation, and the second receivingelectrode 113 functions as the electrode for detecting erroneousdetection. Even though the first receiving electrode 112 detects thevariations in the capacitance, if the second receiving electrode 113detects larger variations in capacitance, it is determined to be theerroneous detection, and thus erroneous operation due to the capacitancevariations, which is not caused by normal operation is prevented.Therefore, for example, a potential to detect operation erroneouslywhich may occur when the person is in proximity to the capacitancesensor electrode 110 but does not perform operation is reduced.

As examples of the capacitance variations which may be caused not by thenormal operation as described above, the case where a person, an animal,or a vehicle passes near by the capacitance sensor electrode 110, andthe case where the vehicle is parked near by the capacitance sensorelectrode 110 are assumed. In such cases as well, the potential todetect operation erroneously is reduced in the same manner. A potentialto detect operation erroneously which may occur when foreign substancessuch as water droplets, frost, snow, mud, and the like are adhered tothe capacitance sensor electrode 110 may also be reduced.

In the illustration in FIG. 2A, the first receiving electrode 112 in thedrawing is arranged on an upper side of the transmitting electrode 111,and the second receiving electrode 113 is arranged on a lower side ofthe transmitting electrode 111. The arrangement of the electrodes is notlimited thereto. Further preferably, however, when the capacitancesensor electrode 110 of the first embodiment is installed on the sidesurface of the vehicle such as the slide door or the rear door, thefirst receiving electrode 112 is arranged on an upper side of thetransmitting electrode 111 and the second receiving electrode 113 isarranged on the lower side of the transmitting electrode 111 in the samemanner as illustrated in FIG. 2A. In other words, an upside and adownside of the capacitance sensor electrode 110 in FIG. 2A preferablymatch the upside and the downside thereof when being installed on theside surface of the vehicle. The same applies to embodiments describedbelow.

In the case where the user operates the capacitance sensor electrode 110with fingers as illustrated in FIGS. 4A and 4B, the palm of the userspontaneously comes to a position apart from the second receivingelectrode 113 when the user operates the first receiving electrode 112located on an upper side with his/her fingers. Accordingly, in the casewhere the normal operation is performed, variations in capacitance valuesatisfy the relationship ΔC1≧ΔC2 spontaneously. Therefore, accuracy ofdiscrimination between the normal operation and the erroneous operationis improved.

In the first embodiment, the surface area of the first receivingelectrode 112 is reduced to be smaller than the surface area of thesecond receiving electrode 113 as a method of reducing the size of thefirst detecting area 301 to be smaller than the second detecting area302. However, the method is not limited thereto. For example, at thetime of a CV conversion performed by the CV converting unit 133, thesizes of the detecting area may be adjusted by setting an amplificationrate when converting the second capacitance value to a voltage value tobe larger than an amplification rate when converting the firstcapacitance value into the voltage value. In the operating unit 124, themagnitudes of values used for determination may be adjusted bymultiplying digital signals corresponding to the first capacitance valueand the second capacitance value by a first coefficient and a secondcoefficient, respectively. In this case, by setting the secondcoefficient to be larger than the first coefficient, the size of thedetecting area may be adjusted in the same manner as the case where thesurface area of the first receiving electrode 112 is set to be smallerthan the surface area of the second receiving electrode 113. It is alsopossible to multiply only the digital signal corresponding to the secondcapacitance value by a coefficient larger than “1”, or to multiply onlythe digital signal corresponding to the first capacitance value by acoefficient smaller than “1”. In the case of adjusting the size of thedetecting area by these methods, the surface area of the first receivingelectrode 112 and the surface area of the second receiving electrode 113may be set as desired. For example, the surface area of the firstreceiving electrode 112 and the surface area of the second receivingelectrode 113 may be the same, and the surface area of the firstreceiving electrode 112 may be larger than the surface area of thesecond receiving electrode 113.

Second Embodiment

In the first embodiment, the capacitance sensor of themutual-capacitance type has been exemplified. However, the capacitancesensor may be of a self-capacitance type. Hereinafter, an example of thecapacitance sensor of the self-capacitance type will be described as asecond embodiment.

FIG. 7A is a drawing illustrating a configuration of a capacitancesensor electrode 110 according to the second embodiment. FIG. 7B is across-sectional view of the capacitance sensor electrode according to athird embodiment taken along a line VIIB-VIIB′. The capacitance sensorelectrode 110 has a first detecting electrode 712 and a second detectingelectrode 713 formed on the base member 211. The first detectingelectrode 712 and the second detecting electrode 713 are arranged inparallel on the same surface of the base member 211. The base member211, the first detecting electrode 712, and the second detectingelectrode 713 all have a laterally elongated rectangular shape. A longside direction of the base member 211, the first detecting electrode712, and the second detecting electrode 713 is substantially the same,and the lengths in the long side direction are substantially the same aswell. The width (the length in a short side direction) of the firstdetecting electrode 712 is smaller than the width of the seconddetecting electrode 713. In other words, a surface area of the firstdetecting electrode 712 is smaller than a surface area of the seconddetecting electrode 713.

FIG. 7C illustrates a distribution of lines of electric force in thecase where the detected object 214 approaches the position in thevicinity of the first detecting electrode 712. The detected object 214equivalently functions as a ground. Therefore, some of the lines ofelectric force output from the first detecting electrode 712 areabsorbed by the detected object 214. Accordingly, the capacitancegenerated by the first detecting electrode 712 is increased. Theincrease of the capacitance is measured via the first detectingelectrode 712, so that approach of the detected object 214 is detected.The same applies to the case where the detected object 214 approachesthe second detecting electrode 713.

The first detecting electrode 712 and the second detecting electrode 713of the second embodiment have functions corresponding to the firstreceiving electrode 112 and the second receiving electrode 113 of thefirst embodiment, respectively. In other words, the first detectingelectrode 712 functions as a detecting electrode for the user operation,and the second detecting electrode 713 functions as the electrode fordetecting erroneous detection. A method of detection is the same as thefirst embodiment, and hence description will be omitted.

The capacitance sensor electrode 110 of the second embodiment ispreferably provided on a rear bumper of the vehicle because the useroperates to open and close a rear door with his or her foot. FIG. 8 is adrawing illustrating a mounting position of the capacitance sensorelectrode 110 on the vehicle according to the second embodiment. Avehicle 800 includes a rear door 801 and a rear bumper 802. Thecapacitance sensor electrode 110 is provided at a center portion of therear bumper 802. The user is capable of opening and closing the reardoor 801 by bringing his or her foot closer to or into contact with therear bumper 802. In this configuration, even when the user holds luggagein both hands, operation with the foot is enabled. The position wherethe capacitance sensor electrode 110 is installed is not limited to thecenter portion of the rear bumper 802, and may be installed at a desiredposition.

In the capacitance sensor 100 of the second embodiment disclosed here,an action of the user approaching his or her foot to the position nearby the first detecting electrode 712 (holding operation) is normaloperation. FIG. 9A is a drawing illustrating a condition in which aperson stands near by the capacitance sensor electrode 110. Thiscondition corresponds to Condition B in Table 1. In the same manner asthe case in FIG. 3 of the first embodiment, the first detecting area 301is smaller than the second detecting area 302. Therefore, the amount ofvariations ΔC1 of the first capacitance value caused by the foot of theperson as the detected object 214 is smaller than the amount ofvariations ΔC2 of the second capacitance value. Therefore, in this case,since relationships ΔC1≧threshold value and ΔC1<ΔC2 are satisfied, thedetermining unit 123 determines that the condition falls under ConditionB, and the user operation is not performed.

In the case where the normal operation illustrated in FIG. 9B isperformed, the foot approaches the first detecting area 301, but thefoot does not approach the position near the second detecting area 302.In other words, in Condition C, the amount of variations ΔC1 of thefirst capacitance value caused by the foot of the person as the detectedobject 214 is not smaller than the amount of variations ΔC2 of thesecond capacitance value. Therefore, since relationships ΔC1≧thresholdvalue and ΔC1≧ΔC2 are satisfied, the determining unit 123 determinesthat the condition falls under Condition C, and the user operation isperformed.

As described above, according to the second embodiment, a capacitancesensor which allows operation of the opening and closing member of thevehicle with a foot is provided, and the potential to detect operationerroneously is reduced in the same manner as in the first embodiment.

In the illustration in FIG. 7A, the first detecting electrode 712 in thedrawing is arranged on a lower side, and the second detecting electrode713 is arranged on an upper side. The arrangement of the electrodes isnot limited thereto. Further preferably, however, when the capacitancesensor electrode 110 of the second embodiment is installed on the rearbumper 802 of the vehicle 800, the first detecting electrode 712 isarranged on the lower side and the second detecting electrode 713 isarranged on the upper side in the same manner as illustrated in FIG. 7A.In the case where the user operates the capacitance sensor electrode 110with his or her foot as illustrated in FIG. 9B, when the user operatesthe first detecting electrode 712 on the lower side with a portion nearthe toe, the portion of the user near the knee is located at a positionaway from the second detecting electrode 713 spontaneously. Therefore,the accuracy of discrimination between the normal operation and theerroneous operation is improved. In the second embodiment, thecapacitance sensor of the self-capacitance type is exemplified. However,the sensor of the mutual-capacitance type as that described in the firstembodiment is also applicable.

Other Embodiment

As other embodiments, a modification of the arrangement of theelectrodes to which the capacitance sensor electrode 110 disclosed hereis applied will be listed. A cross-sectional structure is the same asthose in the first or second embodiment, and thus illustration anddescription will be omitted. In the following description, a principaldifferent point from the first or second embodiment is arrangement ofthe electrodes. Therefore, descriptions of functions and the method ofcontrolling the respective electrodes will be omitted as well.

FIG. 10A and FIG. 10B are drawings illustrating the modifications of thecapacitance sensor electrode 110 of the mutual-capacitance type. FIG.10A illustrates a modification in which the transmitting electrode 111,the first receiving electrode 112, and the second receiving electrode113 are formed on the ellipsoidal base member 211, and the firstreceiving electrode 112 and the second receiving electrode 113 arearranged on both sides of the transmitting electrode 111 in a horizontaldirection. In this modification, since the electrodes are arranged inthe horizontal direction, installation in an area having a small spacein a vertical direction such as a belt molding of the vehicle may bemade. The electrode, having an ellipsoidal shape, may be installedinside an exterior surface of an emblem of the vehicle, for example, sothat the capacitance sensor electrode 110 can be installed on thevehicle without impairing an appearance of the vehicle.

FIG. 10B is a modification in which the shapes of the base member 211,the transmitting electrode 111, the first receiving electrode 112, andthe second receiving electrode 113 in FIG. 10A have a rectangular shapeor a square shape. According to the modification, a surface areaefficiency is better than the above-described ellipsoidal shape, andinstallation may be made in an area having further smaller space.

FIG. 11A to FIG. 11E are drawings illustrating the modifications of thecapacitance sensor electrode 110 of the self-capacitance type. FIG. 11Ais a modification on which the first detecting electrode 712 and thesecond detecting electrode 713 are arranged on the laterally elongatedellipsoidal base member 211. This modification is intended for a casewhere the user operates with his or her hand. In contrast to the caseillustrated in FIG. 7A, more preferably, the first detecting electrode712 is arranged on the upper side, and the second detecting electrode713 is arranged on the lower side. As described in the first embodiment,in the case where the user operates the capacitance sensor electrode 110with his or her hand, the accuracy of discrimination between the normaloperation and the erroneous operation is improved when the firstdetecting electrode 712, which is the detecting electrode operated bythe user, is arranged on the upper side.

FIG. 11B illustrates a modification in which a wide clearance isprovided between the first detecting electrode 712 and the seconddetecting electrode 713. The width of the clearance is preferably largerthan the width of the first detecting electrode 712, for example.Accordingly, the detecting area for detecting the user operation isfurther limited, and hence the accuracy of discrimination between thenormal operation and the erroneous operation is improved.

FIG. 11C is a modification in which the first detecting electrode 712and the second detecting electrode 713 illustrated in FIG. 11A arearranged in the horizontal direction. In the same manner as in FIG. 10A,installation in an area having a small space in the vertical directionis effectively facilitated.

FIG. 11D is a modification in which a clearance between the firstdetecting electrode 712 and the second detecting electrode 713 in FIG.11C is widened. The width of the clearance is preferably larger than thewidth of the first detecting electrode 712, for example. In the samemanner as in FIG. 11B, the accuracy of discrimination between the normaloperation and the erroneous operation is effectively improved.

FIG. 11E is a modification in which the first detecting electrode 712having a rectangular or square shape is provided on the rectangular basemember 211, and the second detecting electrodes 713 having a rectangularor square shape are provided on both sides thereof in the horizontaldirection. In this modification, the second detecting electrodes 713functioning as electrodes for detecting erroneous detection are providedon the both sides of the first detecting electrode 712 in the horizontaldirection. Accordingly, the detecting area for detecting the useroperation is limited, and hence the accuracy of discrimination betweenthe normal operation and the erroneous operation is improved.

An operation detecting apparatus for a vehicle according to an aspect ofthis disclosure includes: a detecting unit including a first electrodeand a second electrode for detecting variations in capacitance value; acapacitance measuring unit configured to measure a first capacitancevalue detected by the first electrode and a second capacitance valuedetected by the second electrode; a determining unit configured tocompare a value on the basis of an amount of variations in the firstcapacitance value with a value on the basis of an amount of variationsin the second capacitance value and determine presence or absence ofoperation from a user on the basis of the result of comparison; and anoutput unit configured to output a control signal on the basis of aresult of determination of the determining unit.

In the operation detecting apparatus for a vehicle, the determining unitmay determine that operation is performed by the user in a case where anabsolute value of the amount of variations in the first capacitancevalue is not smaller than a predetermined threshold value, and theabsolute value of the amount of variations in the first capacitancevalue is not smaller than an absolute value of the amount of variationsin the second capacitance value.

In the operation detecting apparatus for a vehicle, a detecting area ofthe second electrode may be larger than a detecting area of the firstelectrode.

In the operation detecting apparatus for a vehicle, the second electrodemay have a larger surface area than the first electrode.

In the operation detecting apparatus for a vehicle, the capacitancemeasuring unit may include a converting unit configured to convert thefirst capacitance value and the second capacitance value to voltagevalues at a time of measuring, and an amplification rate when convertingthe second capacitance value into the voltage value may be larger thanan amplification rate when converting the first capacitance value intothe voltage value.

The operation detecting apparatus for a vehicle may further include anoperating unit configured to multiply at least one of a value on thebasis of the amount of variations in the first capacitance value and avalue on the basis of the amount of variations in the second capacitancevalue by a coefficient, and multiplication of the coefficient may makethe detecting area of the second electrode larger than the detectingarea of the first electrode.

In the operation detecting apparatus for a vehicle, the determining unitmay determine that operation is not performed by the user in the casewhere the absolute value of the amount of variations in the firstcapacitance value is smaller than a predetermined threshold value.

The operation detecting apparatus for a vehicle may further include athird electrode in addition to the first electrode and the secondelectrode, and the first capacitance value may be a capacitance valuebetween the first electrode and the third electrode, and the secondcapacitance value may be a capacitance value between the secondelectrode and the third electrode.

According to the aspect of this disclosure, an operation detectingapparatus for a vehicle in which the potential to detect operationerroneously is reduced is proposed.

The principles, preferred embodiment and mode of operation of thepresent invention have been described in the foregoing specification.However, the invention which is intended to be protected is not to beconstrued as limited to the particular embodiments disclosed. Further,the embodiments described herein are to be regarded as illustrativerather than restrictive. Variations and changes may be made by others,and equivalents employed, without departing from the spirit of thepresent invention. Accordingly, it is expressly intended that all suchvariations, changes and equivalents which fall within the spirit andscope of the present invention as defined in the claims, be embracedthereby.

What is claimed is:
 1. An operation detecting apparatus for a vehiclecomprising: a detecting unit including a first electrode and a secondelectrode for detecting variations in capacitance value; a capacitancemeasuring unit configured to measure a first capacitance value detectedby the first electrode and a second capacitance value detected by thesecond electrode; a determining unit configured to compare a value onthe basis of an amount of variations in the first capacitance value witha value on the basis of an amount of variations in the secondcapacitance value and determine presence or absence of operation from auser on the basis of the result of comparison; and an output unitconfigured to output a control signal on the basis of a result ofdetermination of the determining unit.
 2. The operation detectingapparatus for a vehicle according to claim 1, wherein the determiningunit determines that operation is performed by the user in a case wherean absolute value of the amount of variations in the first capacitancevalue is not smaller than a predetermined threshold value, and theabsolute value of the amount of variations in the first capacitancevalue is not smaller than an absolute value of the amount of variationsin the second capacitance value.
 3. The operation detecting apparatusfor a vehicle according to claim 1, wherein a detecting area of thesecond electrode is larger than a detecting area of the first electrode.4. The operation detecting apparatus for a vehicle according to claim 1,wherein the second electrode has a larger surface area than the firstelectrode.
 5. The operation detecting apparatus for a vehicle accordingto claim 1, wherein the capacitance measuring unit includes a convertingunit configured to convert the first capacitance value and the secondcapacitance value to voltage values at a time of measuring, and anamplification rate when converting the second capacitance value into thevoltage value is larger than an amplification rate when converting thefirst capacitance value into the voltage value.
 6. The operationdetecting apparatus for a vehicle according to claim 1, furthercomprising: an operating unit configured to multiply at least one of avalue on the basis of the amount of variations in the first capacitancevalue and a value on the basis of the amount of variations in the secondcapacitance value by a coefficient, wherein multiplication of thecoefficient makes the detecting area of the second electrode larger thanthe detecting area of the first electrode.
 7. The operation detectingapparatus for a vehicle according to claim 1, wherein the determiningunit determines that operation is not performed by the user in the casewhere the absolute value of the amount of variations in the firstcapacitance value is smaller than a predetermined threshold value. 8.The operation detecting apparatus for a vehicle according to claim 1,further comprising: a third electrode in addition to the first electrodeand the second electrode, wherein the first capacitance value is acapacitance value between the first electrode and the third electrode,and the second capacitance value is a capacitance value between thesecond electrode and the third electrode.